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Five new cembrane-type diterpenes, lobocalines A–E (1–5), and four new steroids, lobocaloids A–D (9–12), along with six known related compounds (6–8 and 13–15) were isolated from the Yalong Bay soft coral Lobophytum catalai Tixier-Durivault. The structures of the new compounds were elucidated by extensive spectroscopic analysis, NMR calculation with DP4+ analysis, time-dependent density functional theory–electronic circular dichroism (TDDFT-ECD) calculations, X-ray diffraction analyses and comparison with the reported spectroscopic data of known compounds. Further, with the aid of X-ray diffraction analysis, the structure of lobocrasol B (15) was firmly revised as 15a. In in vitro bioassays, compound 2 showed moderate antibacterial activities against fish pathogenic bacteria Streptococcus parauberis KSP28 and Phoyobacterium damselae FP2244 with minimum inhibitory concentration (MIC) values of 8.7 and 17.3 µg/mL, respectively. All the steroids exhibited antibacterial activities against the S. parauberis KSP28 with MIC values ranging from 12.3 to 53.6 µg/mL. Compounds 2, 7 and 14 have remarkable inhibitory effects on the hemolysin production of Staphylococcus aureus, while compounds 8–12 have medium inhibitory effects on the pyocyanin production in Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Nanolobatone A, featuring an unprecedented tricyclo[10.3.0.01,2]pentadecane carbon skeleton, along with four new polyoxygenated and four unusual endoperoxide‐bridged casbane‐type diterpenoids were isolated from the Hainan soft coral Sinularia nanolobata. The structures of the new compounds were established by extensive spectroscopic analysis, X‐ray diffraction analysis, and time‐dependent density functional theory/electronic circular dichroism calculations. A plausible biosynthetic pathway of new isolates was proposed. Bioassays revealed that nanolobatone A showed weak antibacterial activity against the Gram‐positive bacteria Streptococcus pyogenes. [ABSTRACT FROM AUTHOR]

Documents on the chemical composition of the soft coral Sarcophyton mililatensis are sparse. The present investigation of the Hainan soft coral S. mililatensis resulted in the discovery of six new cembrane diterpenes, sarcoxacyclols A–F (1–6) and four known analogs (7–10). Their structures were elucidated by extensive spectroscopic analysis along with a comparison with the data in current literature. The nonaromatic oxacycles in their structures were the rarely found tetrahydrofuran ether across C-1 and C-12 and tetrahydropyran ether across C-1 and C-11, respectively. Moreover, the absolute configuration of compound 4 was established unambiguously by X-ray diffraction analysis using Ga Kα radiation (λ = 1.34139 Å). Based on the biogenetical consideration, the absolute configurations of other five new compounds were tentatively assumed. Assessment of the bioactivity for these secondary metabolites revealed that compound 1 exhibited significant tumor necrosis factor (TNF)-α inhibitory activity (IC50 = 9.5 μmol/L), similar to the positive control dexamethasone (IC50 = 8.7 μmol/L), but no obvious cytotoxicity towards RAW264.7 cells (CC50 > 50 μmol/L). The preliminary molecular docking suggested the crucial roles of the hydroxyl and acetoxyl groups in the computational prediction of the binding mode between the diterpene and the protein. [ABSTRACT FROM AUTHOR]

Three unusual diterpenes with rare sarsolenane and capnosane skeletons, namely mililatensols A–C (1–3), were isolated from the South China Sea soft coral Sarcophyton mililatensis, leading to the first record of sarsolenane and capnosane diterpenes from the title animal. The structures of compounds 1–3 were established by extensive spectroscopic analysis and comparison with the literature data. Moreover, the absolute configuration of 2 was determined by TDDFT ECD calculations. In an in vitro bioassay, none of the isolated compounds showed obvious anti-inflammatory activity on LPS-induced TNF-α release in RAW264.7 macrophages. In the preliminary virtual screening of inhibitory potential against SARS-CoV-2 by molecular docking, the results showed these three diterpenes were potential SARS-CoV-2 Mpro inhibitors. [ABSTRACT FROM AUTHOR]

• Eight new diterpenoids were isolated from the Xisha soft coral Lobophytum sp. • The RCs of all the new molecules were successfully elucidated through QM-NMR method. • The AC of 8 was established by the modified Mosher's method & chemical transformation. • Compound 4 exhibited promising cytotoxicities against several human tumor cell lines. Seven new cembrane-type diterpenes, lobophytolins C–I (3 – 9), and one new prenylated-guiane-type diterpene, lobophytolin J (10), along with six known related ones (1 , 2 , 11 – 14), have been isolated from the soft coral Lobophytum sp. collected off the Xisha Island in the South China Sea. Their structures were elucidated by extensive spectroscopic analysis and quantum mechanical (QM)-NMR methods. The absolute configuration of lobophytolin H (8) was determined by the application of the modified Mosher's method and chemical transformation. Lobophytolin D (4) exhibited promising cytotoxicities in in vitro bioassays against HT-29, Capan-1, A549, and SNU-398 human cancer cell lines with IC 50 values of 4.52, 6.62, 5.17, and 6.15 μM, respectively. [ABSTRACT FROM AUTHOR]

Molecular networking strategy-based prioritization of the isolation of the rarely studied soft coral Sinularia tumulosa yielded 14 sesquiterpenes. These isolated constituents consisted of nine different types of carbon frameworks, namely asteriscane, humulane, capillosane, seco-asteriscane, guaiane, dumortane, cadinane, farnesane, and benzofarnesane. Among them, situmulosaols A–C (1 , 3 and 4) were previously undescribed ones, whose structures with absolute configurations were established by the combination of extensive spectral data analyses, quantum mechanical-nuclear magnetic resonance and time-dependent density functional theory electronic circular dichroism calculations, the Snatzke's method, and the modified Mosher's method. Notably, situmulosaol C (4) was the second member of capillosane-type sesquiterpenes. The plausible biogenetic relationships of these skeletally different sesquiterpenes were proposed. All sesquiterpenoids were evaluated for their antibacterial, cytotoxic and anti-inflammatory effects. The bioassay results showed compound 14 exhibited significant antibacterial activities against a variety of fish and human pathogenic bacteria with MIC 90 values ranging from 3.6 to 33.8 μg/mL. Moreover, moderate cytotoxic effects against HEL cells for components 13 and 14 and moderate inhibitory effect on lipopolysaccharide-induced inflammatory responses in RAW264.7 cells for substance 13 were also observed. [Display omitted] • 14 sesquiterpenes were isolated from Sinularia tumulosa applying molecular networking. • These isolates possessed nine different carbon frameworks. • Situmulosaol C (4) was the second member of capillosane-type sesquiterpenes. • Absolute configurations were assigned by QM-NMR, TDDFT ECD, ICD, and Mosher's method. • Compound 14 showed significant antibacterial and moderate cytotoxic activities. [ABSTRACT FROM AUTHOR]

The chemical investigation on the soft coral Sinularia brassica collected off Xuwen Country, Guangdong Province, China, has resulted in the isolation and characterization of three uncommon cycloamphilectane-type diterpenoids, namely sinucycloamtin A–C (1 – 3), along with two known analogues (5 and 6). In addition, compounds 2 and 3 were hydrolyzed and their hydrolytic derivative sinucycloamtin D (4) was obtained. The structures of these previously undescribed compounds were established on the basis of extensive spectroscopic analysis, X-ray diffraction analysis, chemical conversion, as well as the comparison with the literature reported data. Compounds 1 – 3 represented the first examples of benzene-containing cycloamphilectane-type diterpenoids isolated from soft coral of genus Sinularia. In the in vitro bioassays, all the isolated and derived diterpenoids exhibited significant antibacterial activities against the fish pathogenic bacteria Phoyobacterium damselae FP2244 and Streptococcus parauberis SPOF3K with MIC 90 values ranging from 3.7 to 9.1 μM. [Display omitted] • Four uncommon diterpenoids were characterized from soft coral Sinularia brassica. • The structures of isolated compounds were unambiguously elucidated. • All isolates and derivative were evaluated for their antibacterial activities. [ABSTRACT FROM AUTHOR]

• Two uncommon norhumulene-type terpenoids were isolated from the South China Sea soft coral Sinularia hirta. • Their structures were determined by 1D/2D NMR, ECD calculation and GIAO 13C NMR calculation. • A plausible biogenetic relationship of 1–4 was proposed. Two new uncommon norhumulene-type norsesquiterpenoids, namely sinuhirtins A (1) and B (2), along with two known norcaryophyllene-type norsesquiterpenoids (3 and 4), were isolated from the South China Sea soft coral Sinularia hirta. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic data analyses, and computer-assisted methods including GIAO 13C NMR and TDDFT-ECD calculations. A plausible biogenetic relationship of 1 – 4 was proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four new oxygenated steroids were isolated from Sinularia depressa. • New compounds sinulasterols D and E featured on uncommon C-18 oxygenated pattern. • Sinulasterols D-F exhibited interesting antibacterial activity. Four new steroids, namely sinulasterols D–G (1–4), along with seven known related ones 5–11 , were isolated from the Xisha soft coral Sinularia depressa. The structures of the new compounds were elucidated by a combination of extensive spectroscopic analyses, chemical conversion method, and comparison of the NMR data with those of known analogues. In in vitro bioassays, compounds 1–3 showed significant antibacterial activities against gram-positive bacteria Enterococcus faecium with minimum inhibitory concentration (MIC) values of 62.5, 125, and 125 µM, respectively, comparable with that of vancomycin (MIC: >44.2 µM). [ABSTRACT FROM AUTHOR]

Four new polyoxygenated cembranoids, namely sarcoboettgerol A (1), 12- epi -humilisin D (2), sarcoboettgerol B (3), and sarcoboettgerol C (4), together with one known related analogue, humilisin D (5), were isolated and characterized from the soft coral Sarcophyton boettgeri collected off Ximao island, Hainan Province, China. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic data analyses, Cu k α single crystal X-ray diffraction analysis, and TDDFT-ECD calculations. A plausible biogenetic relationship of 3 and 4 was proposed. [Display omitted] [ABSTRACT FROM AUTHOR]